1. Field of the Invention
The present invention relates to a method and a system to adjust the horsepower output of an internal combustion engine having an electronic control with programmable memory to within a target range such that it is possible to manufacture engines of the same make and model having greater uniformity of engine horsepower when comparing engines within a given series.
The present invention further relates to a method and a system for adjusting the horsepower output of an internal combustion engine having an electronic control with programmable memory, at least one cylinder, and at least one fuel injector in fuel delivery communication with said cylinder by measuring the horsepower developed by the engine during normal operation, and adjusting the fuel dispensed by the fuel injectors as needed in order to adjust the horsepower developed by an engine to a target or nominal range.
The present invention further relates to a method and a system for controlling the horsepower output of a compression ignition internal combustion engine, such as a diesel engine, so that the engines of a given series conform more uniformly to a target horsepower output range.
2. Description of the Related Art
Electronic controllers for internal combustion engines are old and well known in the art. In diesel engines, the conventional practice utilizes electronic control units having volatile and nonvolatile memory, input and output driver circuitry, and a processor capable of executing a stored instruction set, to control the various functions of the engine and its associated systems. A particular electronic control unit communicates with numerous sensors, actuators and other electronic control units necessary to control various functions which may include aspects of fuel delivery.
During engine manufacturing, or during engine service life, a certain range of engine horsepower output which differs from the target or nominal horsepower rating has been tolerated because there has been no easy way to ensure that an engine rated at a certain horsepower accurately developed that rated or nominal horsepower. If the horsepower developed by an engine is too high for a given nominal rating, the engine suffers premature wear with resulting lessening of engine life. Moreover, operators of vehicles equipped with such engines experienced uncertainty in duty cycles and hauling capabilities because the horsepower rating varied over such a wide range for a given manufacturer's model series. Thus, uniformity of engine models within a fleet of vehicles with such engines was still no guarantee that each engine developed the same horsepower, or was capable of hauling the same loads and acting the same way over the same route. This unpredictable effect is costly to the fleet owner in terms of fuel consumption and engine service life.
Weisman et al., U.S. Pat. No. 5,477,827 discloses a method for comprehensive control of an internal combustion engine, such as a compression ignition engine, utilizing an electronic control module. The control strategy integrates various functions of engine control including an acceleration balance test for the engine cylinders, a fuel economy vehicle speed limit adder, a fueling limit for high altitude vehicle operation, throttle logic, a data-hub for operation trending and vehicle component lifting analyses, a gear ratio torque limit, an air temperature based torque limit, enhanced fan control, and an idle shutdown strategy based on ambient temperature. Included within the '827 patent is a method for balancing the fuel injectors. The method comprises operating the engine at a predetermined idle speed so as to permit the engine to stabilize, and cutting off the fuel delivered by the fuel injectors to at least one of the cylinders. The method further comprises measuring the acceleration RPM of the engine with at least one cylinder cut out, and modifying the fuel delivered from the fuel injectors based on the measured acceleration RPM so as to balance the power output of each cylinder. The balancing of the cylinders is done so as to reduce particulate emissions, improve fuel economy and reduce localized engine wear. There is no showing that it is possible to adjust the horsepower output of the engine to a target range which is uniform within a nominal target range.